1. Field of the Invention
The present invention relates to a multi-function machine tool in which a workpiece held by workpiece attachment means on the tip end of a rotatable main spindle is machined by a tool mounted on a turning tool rest that is capable of a turning motion and a linear motion in two or more directions, and a machining method of this multi-function machine tool; more particularly, the present invention relates to a multi-function machine tool which can machine helical grooves of diverse shapes in the workpiece, and a machining method of this multi-function machine tool.
2. Description of the Related Art
The techniques described in Japanese Patent Publication No. H6-506640 (International Publication No. WO92/18278) and Japanese Patent Application Laid-Open No. 3170790 and the like (described later) are known as methods for machining helical grooves of complex shapes in workpieces. A method for forming helical grooves in a screw compressor by rotating the workpiece and rotating the tool is described in Japanese Patent Publication No. H6-506640. However, the machine tool used to carry out this method is a special tool, and arbitrary setting of the groove width, groove radius (rotating radius of the tool), groove cross-sectional shape and the like is difficult. Furthermore, since a special tool must be introduced in order to perform this machining, the cost of machining is increased.
A method for machining cam grooves in a roller cam by rotating the workpiece, rotating a table and moving the tool in the directions of the X axis and Y axis is described in Japanese Patent Application Laid-Open No. 3170790. Here, however, there is no concrete description of exactly how the rotating of the table and the movement of the tool in the directions of the X axis and Y axis are performed in order to machine grooves of a desired shape, and it is unclear exactly what type of NC machining program is necessary for the actual machining of grooves. Accordingly, it is necessary to calculate the movement track of the tool used to machine the desired shape and the like by means of a computer or the like, and the actual NC machining program must be prepared from the results of these calculations.
Thus, in order to machine helical grooves of complex shapes in a workpiece, it has conventionally been necessary to use a special tool, which has led to an increase in machining costs; furthermore, it has been difficult to set the groove width, groove radius, groove cross-sectional shape and the like at arbitrary values. Moreover, in the case of machine tools in which the machining of grooves is performed by combining the rotating of the table and the movement of the tool along the X and Y axes, calculation of the movement path of the tool is complicated.